Recently, secondary batteries, which can be charged and discharged, have been widely used as energy sources for wireless mobile devices. Secondary batteries have also attracted considerable attention as power sources for electric vehicles (EV), hybrid electric vehicles (HEV) and plug-in hybrid electric vehicles (plug-in HEV), which have been developed to solve problems, such as air pollution, caused by existing gasoline and diesel vehicles that use fossil fuels.
Small-sized mobile devices use one or several battery cells for each device. On the other hand, middle or large-sized devices such as vehicles use a battery module including a number of battery cells electrically connected to each other because high power and large capacity are necessary for the middle or large-sized devices.
Since the battery module is preferably manufactured to have as small a size and weight as possible, prismatic batteries or pouch-shaped batteries, which can be stacked with high integration and have a small weight to capacity ratio, are usually used as battery cells of middle or large-sized battery modules. In particular, much interest is currently focused on pouch-shaped batteries, which use an aluminum laminate sheet as a sheathing member, due to their advantages of being lightweight and cheap to manufacture.
In addition, since the battery module is made up by combining a number of battery cells, safety and operating efficiency of the battery module are considerably deteriorated when some of the battery cells suffer from overvoltage, overcurrent or overheat. Therefore, it is necessary to provide a means for sensing and controlling such overvoltage, overcurrent or overheat. Thus, voltage sensors or the like are connected to the battery cells to check and control operating states of the battery cells in real time or at predetermined intervals. However, installation or connection of such measuring members greatly complicates the process of assembling the battery module and may cause a short circuit due to use of many wires. Further, as the secondary battery is used as a power source for vehicles as a result of extension of the application range of the secondary battery, there is a need to provide a fastening means to maintain the sensing means in a stable contact state even when strong impact or vibration is applied to the battery module.
In addition, when a battery module is constructed using a plurality of battery cells or is constructed using a plurality of cell modules, each including a specific number of battery cells, it is generally necessary to provide a large number of members for mechanical coupling and electrical connection between the battery cells or the unit modules and therefore the process of assembling such members is very complicated.
Furthermore, spaces for coupling, welding, or soldering of the members are needed to achieve such mechanical coupling and electrical connection, thereby increasing overall battery system size. Such size increase is undesirable as previously described.
In addition, when additional assembly parts such as receptacle terminals are used, there is a problem in that correct voltage sensing is not easy due to contact resistance at contact portions of the assembly parts.
Thus, there is a great need to provide a voltage sensing assembly, which is more compact and exhibits improved voltage sensing reliability while fundamentally solving the above problems, and a battery module including the same.